Multiple slot load lock chamber and method of operation

ABSTRACT

Embodiments of the invention include a load lock chamber, a processing system having a load lock chamber and a method for transferring substrates between atmospheric and vacuum environments. In one embodiment, the method includes maintaining a processed substrate within a transfer cavity formed in a chamber body for two venting cycles. In another embodiment, the method includes transferring a substrate from a transfer cavity to a heating cavity formed in the chamber body, and heating the substrate in the heating cavity. In another embodiment, a load lock chamber includes a chamber body having substrate support disposed in a transfer cavity. The substrate support is movable between a first elevation and a second elevation. A plurality of grooves are formed in at least one of a ceiling or floor of the transfer cavity and configured to receive at least a portion of the substrate support when located in the second elevation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to a load lock chamber fora vacuum processing system, and a method for operating same.

2. Description of the Related Art

Two rapidly evolving technology areas are thin film transistors andphotovoltaic devices. Thin film transistors (TFT) formed by flat paneltechnology are commonly used for active matrix displays such as computerand television monitors, cell phone displays, personal digitalassistants (PDAs), and an increasing number of other devices. Generally,flat panels comprise two glass plates having a layer of liquid crystalmaterials sandwiched therebetween. At least one of the glass platesincludes one conductive film disposed thereon that is coupled to a powersource. Power, supplied to the conductive film from the power source,changes the orientation of the crystal material, creating a patterndisplay.

Photovoltaic devices (PV) or solar cells are devices which convertsunlight into direct current (DC) electrical power. PV or solar cellstypically have one or more p-n junctions formed on a panel. Eachjunction comprises two different regions within a semiconductor materialwhere one side is denoted as the p-type region and the other as then-type region. When the p-n junction of the PV cell is exposed tosunlight (consisting of energy from photons), the sunlight is directlyconverted to electricity through the PV effect. In general, a highquality silicon-based material is desired to produce high efficiencyjunction devices (i.e., high power output per unit area). Amorphoussilicon (a-Si) film has been widely used as the silicon-based panelmaterial in PV solar cells due to its low cost to manufacture inconventional low temperature plasma enhanced chemical vapor deposition(PECVD) processes.

With the marketplace's acceptance of flat panel technology and desirefor more efficient PV devices to offset spiraling energy costs, thedemand for larger panels, increased production rates and lowermanufacturing costs have driven equipment manufacturers to develop newsystems that accommodate larger size substrates for flat panel displayand PV device fabricators. Current substrate processing equipment isgenerally configured to accommodate substrates slightly greater thanabout two square meters. Processing equipment configured to accommodatelarger substrate sizes is envisioned in the immediate future.

Equipment to fabricate such large substrates represents a substantialinvestment to fabricators. Conventional systems require large andexpensive hardware. In order to offset this investment, high substratethroughput is very desirable.

Heating and/or cooling of the substrate within the load lock chamber isan important aspect for achieving high system throughput. As futureprocessing systems are envisioned to process even larger sizesubstrates, the need for uniform rapid heating and cooling of large areasubstrates is of great concern. As such, advancements which promoteuniform temperature regulation and high heat transfer rates are highlydesirable.

Thus, there is a need for an improved method and apparatus thatfacilitates rapid and uniform heating and cooling of larger areasubstrates.

SUMMARY OF THE INVENTION

Embodiments of the invention include a load lock chamber, a processingsystem having a load lock chamber and a method for transferringsubstrates between an atmospheric environment and a vacuum environment.In one embodiment, a method for transferring substrates betweenatmospheric and a vacuum environments includes maintaining a processedsubstrate within a substrate transfer cavity formed in a load lockchamber body for two venting cycles. In another embodiment, a method fortransferring substrates includes transferring a substrate from atransfer cavity to a heating cavity formed in the load lock chamberbody, and heating the substrate in the heating cavity.

In another embodiment, a load lock chamber is provided that includes achamber body having a substrate support disposed in a substrate transfercavity. The substrate support is movable between a first elevation and asecond elevation. A plurality of grooves are formed in at least one of aceiling or floor of the substrate transfer cavity and configured toreceive at least a portion of the substrate support when located in thesecond elevation.

In yet another embodiment, a substrate processing system is providedthat includes substrate transfer chamber having a substrate transferrobot disposed therein, one or more vacuum processing chambers coupledto the transfer chamber and a load lock chamber. The load lock chamberhas a body that is coupled to the transfer chamber. The body of the loadlock chamber includes first and second cooled transfer cavities and aheating cavity. Each of the cooled transfer cavities has a plurality ofsubstrate storage slots.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the inventionare attained and can be understood in detail, a more particulardescription of the invention, briefly summarized above, may be had byreference to the embodiments thereof which are illustrated in theappended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a plan view of an illustrative cluster tool having oneembodiment of a load lock chamber of the present invention;

FIG. 2 is a sectional view of the load lock chamber taken along sectionline 2-2 of FIG. 1;

FIG. 3 is a partial sectional view of the load lock chamber of FIG. 1;

FIG. 4A is another partial sectional view of the load lock chamber ofFIG. 1;

FIG. 4B is a partial isometric view of another embodiment of an interiorof a load lock chamber;

FIG. 4C is a partial sectional view of another embodiment of an interiorof a load lock chamber;

FIG. 5 is another partial sectional view of the load lock chamber ofFIG. 1;

FIG. 6 is a flow diagram of one embodiment of a method for transferringsubstrate between an atmospheric environment and a vacuum environment;

FIG. 7 is another embodiment of a flow diagram of one embodiment of amethod for transferring substrates between an atmospheric environmentand a vacuum environment;

FIG. 8 is a side sectional view of another embodiment of a multiplechamber load lock chamber;

FIG. 9 is a flow diagram of another embodiment of a method fortransferring substrates between an atmospheric environment and a vacuumenvironment; and

FIG. 10 is a graph illustrating the vacuum condition of one cavity ofthe load lock chamber of FIG. 8 having the method of FIG. 9 practicedtherein.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures. It is contemplated that elements of one embodiment maybe advantageously utilized in other embodiments without furtherrecitation.

DETAILED DESCRIPTION

A load lock chamber suitable for efficient heating and cooling of largearea substrates is provided. A method for utilizing the load lockchamber to transfer substrates between a vacuum environment, such aspresent in a transfer chamber, and an atmospheric environment, such aspresent in a factory interface, is also provided. Although specificembodiments of both load lock chambers and a method of transferringsubstrates are provided below with reference to a load lock chamber of aconfiguration available from Applied Materials, Inc., of Santa Clara,Calif., it is contemplated that the inventive features and methods maybe adapted for use in other load lock systems, including those fromother manufacturers.

FIG. 1 is a plan view of an illustrative cluster tool 100 having oneembodiment of a load lock chamber 104 of the present invention. Thecluster tool 100 includes a factory interface 102 coupled by the loadlock chamber 104 to a transfer chamber 106. The factory interface 102generally includes a plurality of substrate storage cassettes 114 and anatmospheric robot 112. The atmospheric robot 112 facilitates transfer ofsubstrates 116 between the cassettes 114 and the load lock chamber 104.A plurality of substrate processing chambers 108 are coupled to thetransfer chamber 106. A vacuum robot 110 is disposed in the transferchamber 106 to facilitate transfer of a substrate 116 between the loadlock chamber 104 and the processing chambers 108.

The load lock chamber 104 generally includes a plurality ofenvironmentally-isolatable cavities, each having one or more substratestorage slots defined therein. The load lock chamber 104 is operated totransfer substrates 116 between an ambient or atmospheric environment ofthe factory interface 102 and the vacuum environment maintained in thetransfer chamber 106.

FIG. 2 depicts one embodiment of a load lock chamber 104 of the presentinvention. The load lock chamber 104 includes a body assembly 202fabricated from a rigid material such as stainless steel, aluminum orother suitable material. The body assembly 202 may be fabricated from anassembly of components into a leak-free structure. One suitable bodyassembly that may be adapted to benefit from the invention is describedin U.S. patent application Ser. No. 11/332,781, filed Jan. 13, 2006,which is incorporated by reference in its entirety. Alternatively, thebody assembly 202 may have other configurations and/or be fabricatedfrom a single block of material.

In one embodiment, the body assembly 202 includes a top plate 204 and abottom plate 206 that sandwich a plurality of ring-shaped bodies 248.Interior plates 198 are disposed between the bodies 248. The plates 204,206, 298 enclose internal volumes 220 defined inside each of the bodies248. In the embodiment depicted in FIG. 2, the upper and lower internalvolumes 220 are configured as substrate transfer cavities 208, 210,while the internal volume 220 bounded by the middle body 248 isconfigured as a heating cavity 212.

The top and bottom plates 204, 206 are sealingly coupled to the bodies248 by a plurality of fasteners in a manner that permits relativemovement between at least one of the top and bottom plates 204, 206 andthe body 248. For example, at least one of the top and bottom plates204, 206 are coupled to the body 248 without welding. In embodimentswherein force applied to the sidewalls from the plates 204, 206 is notof great concern, the top and bottom plates 204, 206 and the body 248may be coupled by welding.

Referring additionally to a partial sectional view of the body assembly202 depicted in FIG. 3, at least one spacer 316 is provided between alower surface 302 of the top plate 204 and an upper surface 304 of thebody 248. The spacer 316 separates the top plate 204 and chamber body248, such that a gap 306 is defined therebetween. In one embodiment, thespacer 316 is a member having a plan area much smaller than the planarea of the upper surface 304 of the chamber body 248. For example, aplurality of spacers 316 may be disposed on upper surface 304 along oneside of the chamber body 248.

The thickness of the spacer 316 is selected such that a gasket or o-ring386 is adequately compressed to maintain a vacuum seal between theplates and body, while preventing the top plate 204 from contacting thechamber body 248 under vacuum or other stress conditions. Similarly, oneor more spacers 316 are provided between the bottom plate 206 and thechamber body 248 to maintain a gap 306 therebetween.

In one embodiment, the body assembly 202 includes a top plate 204 and abottom plate 206 that sandwich a plurality of ring-shaped bodies 248.Interior plates 298 are disposed between the bodies 248. The plates 204,206, 298 enclose internal volumes 220 defined inside each of the bodies248. In the embodiment depicted in FIG. 2, the upper and lower internalvolumes 220 are configured as substrate transfer cavities 208, 210,while the internal volume 220 bounded by the middle body 248 isconfigured as a heating cavity 212.

In one embodiment, the spacers 312, 314 are disks. The disks may bewashers disposed around the bolts 282 utilized to secure the bodyassembly 202 for ease of assembly. As the sliding components (e.g., thespacers 312, 314) have reduced contact area relative to the uppersurface 304 of the body 248, the force necessary to begin motion isreduced. Additionally, as the contacting surface of the spacers 312, 314are outward of the gasket 386, any particles generated during thesliding of the spacers 312, 314 are beneficially prevented from enteringthe internal volume 220 of the load lock chamber 104. It is contemplatedthat the spacers 316 may be in the form of a rib or other feature,extending between the plates and body to maintain a gap therebetween. Itis also contemplated that the spacer may be incorporated into either theplates or body. It is contemplated that the spacers 316 may be in theform of a rib or other feature extending between the plates and body tomaintain a gap therebetween. It is also contemplated that the spacer maybe incorporated into either the plate or body (i.e., have unitaryconstruction).

In the embodiment depicted in FIG. 3, a recess 308 is formed in theupper surface 304 of the body 248 to locate the second spacer 314.Optionally, a recess (not shown) may be formed in the top plate 204 tolocate the first spacer 312. The recess (not shown) 308 has a depthselected, such that the spacer 314 extends beyond the upper surface 304to ensure the first spacer 312 is free to slide laterally relative tothe body 248.

To further minimize the effect of forces exerted on the top plate 204 ofthe load lock chamber 104, at least one slot 318 is formed therein. Theslots 318 allow the central region of the top plate 204 to move, deflectand/or expand while minimizing the effect of motion on the edges of thetop plate. A seal assembly 320 disposed in the slot 318 to preventleakage into interior volume 220 of the load lock chamber 104. In theembodiment depicted in FIG. 3, the seal assembly 320 includes gasket orbellows 322 clamped to the top plate 204 by a clamp block 324.Similarly, the bottom plate 206 includes at least one slot 330 sealed bya seal assembly 320, as described above.

Returning back to FIG. 2, two substrate access ports 216 are formedthrough opposing sidewalls of the bodies 248 to allow entry and egressof substrates from the internal volume 220 of the substrate transfercavities 208, 210. Only one of the ports 216 are shown in FIG. 2. Theheating cavity 212 includes at least one substrate access port 216defined on a side of the body 248 that is coupled to the transferchamber 106 so that the interior volume 220 of the transfer cavity 212may be accessed by the vacuum robot 110 (shown in FIG. 1). The substrateaccess ports 216 are selectively sealed by slit valve doors, which arewell known in the art. One slit valve door that may be adapted tobenefit from the invention is described in U.S. patent application Ser.No. 10/867,100, entitled CURVED SLIT VALVE DOOR, filed Jun. 14, 2004 byTanase, et al., and is incorporated by reference in its entirety.

The heating cavity 212 may optionally have a second substrate accessport (not shown in FIG. 2). The second substrate access port may beselectively sealed by a slit valve door, or alternatively sealed by ablank plate since the substrate access port is primarily used for cavitymaintenance.

In one embodiment, at least one of the plates 204, 206, 298 may beconfigured as a temperature regulating plate. One or more passages 224may be formed in the plates 204, 206, 298 and coupled to a fluid source228. The fluid source 228 provides a heat transfer fluid that iscirculated through the passages 142 to regulate (i.e., heat and/or cool)the temperature of the plates 204, 206, 298 and ultimately, thetemperature of the substrate 116. By cooling the plates 204, 206, 298,hot substrates returning from processing may be effectively cooledwithout utilizing a separate conventional cooling plate disposed withinthe cavities 208, 210.

The heating cavity 212 generally includes one or more heaters 266disposed in the internal volume 220 that are to selectively heat thesubstrate 116. In the embodiment depicted in FIG. 2, a plurality ofheaters 266 are coupled to at least one of the surfaces of the interiorplates 298 facing the substrate 116 disposed in the heating cavity 212.The heaters 266 may be lamps, resistive heating elements or othersuitable heating device. The position of the heaters 266 above and belowthe substrate 116 facilitates rapid radiant heating of the substrate.The heaters 266 are independently coupled to a power source 268. Thisconfiguration allows each heater 266 to be independently controlled sothat the temperature profile of the substrate 116 may be tailored asdesired, for example, by uniformity heating and/or by heating one regionof the substrate faster than a second region. In the embodiment depictedin FIG. 2, the heaters 266 are arranged to allow the center of thesubstrate 116 to be heated at a rate different than the perimeter of thesubstrate.

Referring to FIGS. 2 and 4A, a plurality of substrate support structures218 are disposed in the internal volumes 220 of the transfer cavities208, 210. The substrate support structures 218 are generally configuredto each support a single substrate. The elevation of the supportstructures 218 is selectively controlled such that the proximity ofsubstrate to the cooled plates (or heaters 266) may be selectivelyadjusted. The elevation of the support structures 218 may also becontrolled to facilitate substrate exchange through the ports 216. Inone embodiment, each substrate support 218 is coupled to one or moreactuators 294 so that the elevation of the respective supports 218within each cavity may be independently controlled. It is contemplatedthat other substrate support structures may alternatively be used.

In one embodiment, the substrate support structure 218 includes a plateor plurality of bars 296 coupled to the actuators 294. The bars 296 areconfigured to span beyond the underside of the substrate supportedthereon to facilitate coupling of the bar to the actuator 294.

A plurality of pins 226 may extend from the bars 296 to support thesubstrate 116 thereon. The ends of the pins 226 supporting the substrate116 may be rounded and/or include a ball to reduce dynamic frictionbetween the bottom surface of the substrate 116 and the pins 226 and toprevent substrate scratching. In the embodiment depicted in FIG. 2, aball is disposed at a distal end of each pin 226. The reduced frictionprovided by the balls allows the substrate to readily expand andcontract while supported on the pins 226 without scratching thesubstrate. Other suitable substrate supports are described in U.S. Pat.No. 6,528,767, filed Mar. 5, 2003; U.S. patent application Ser. No.09/982,406, filed Oct. 27, 2001; and U.S. Patent Application No.60/376,857, filed Feb. 27, 2003, all of which are incorporated byreference in their entireties. The pins 226 are generally arranged tofacilitate substrate exchange with a robotic end effector. Pins 226 areadditionally coupled to the interior plate 298 forming the floor of theheating cavity 212 to support a substrate therein.

To enhance heat transfer between the substrate and the chamber body 248,the substrate supports 218 may move the substrate support thereonproximate the floor (or ceiling) of the transfer cavities 208, 210. Thedistance between the substrate and transfer cavity floor/ceiling may beadjusted based on the temperature of the substrate. For example, hotsubstrate returning from pressing may have temperatures in excess of 240degrees Celsius. To prevent condensation and/or thermal stress forforming, the hot substrate may be maintained at a large distance fromthe transfer cavity floor/ceiling. Once the hot substrate has beensufficiently cooled, for example to about 140 degrees Celsius, thecooler substrate may be moved closer to the transfer cavityfloor/ceiling to increase the heat transfer efficiency, thereby allowingcooler substrate temperatures to be obtained at a faster rate, whichalso enhances substrate throughput.

To further enhance heat transfer between the substrate and thefloor/ceiling of the transfer cavities 208, 210, the substrate supports218 may be configured to interfit with the floor and/or ceiling of thetransfer cavity. This allows the distance between the substrate andchamber body assembly 202 to be minimized, and in some embodiments, toplace the substrate in contact with the chamber body assembly 202 totake full advantage of thermal exchange with the heat transfer fluidrunning through the passages 224.

FIG. 5 depicts a sectional view of one embodiment of the interior plate298 configured to interfit with the substrate support 218. The plate 298includes slots 502 (one is shown in FIG. 5) that are configured to allowthe bar 296 of the substrate support 218 to be moved therein. In oneembodiment, the depth of the slot 502 may be selected to allow thesubstrate to be lifted from the pins 226 by the plate 298 as the bar 296moves to the bottom of the slot 502. Alternatively, the slot 502, ormotion of the bar 296, may be configured to maintain the substrate 116,supported on the pins 226, in close proximately to the plate such thesubstrate is efficiently cooled by the fluid circulating through thepassages 224. The second transfer cavity 210 is similarly configuredwith slots 502 formed in the lower portion of the bounding internalplate 298.

FIG. 4B is a partial isometric view of another embodiment of an interiorof the load lock chamber. In the embodiment depicted in FIG. 4B, theactuator 404 which controls the elevation of the lower substrate support444 passes through a feature 440 formed in the upper substrate support442, thereby enabling the actuators 402, 406 to be aligned. Thus, thesubstrate supports 442, 444 may be configured to have the same projectedsurface area (e.g., footprint) within the interior volume of the loadlock chamber, thereby enabling the walls of the load lock chamber bodyto be disposed closer to the substrate supports 442, 444, which reducesthe interior volume of the load lock chamber beneficially resulting inlower pumping and venting times. In the embodiment depicted in FIG. 4B,the feature 440 is a hole formed through the upper substrate support442. It is contemplated that the feature 440 may alternatively be anotch, a groove, a slot, cut-out or other geometric disparity betweenthe upper and lower substrate supports 442, 444 which enable theactuator 402 controlling the elevation of the lower substrate support444 to be coupled to the lower support plate 444 without obstruction byupper substrate support 442. It is also contemplated that pairs of theactuators 402, 404 may be concentrically aligned, with the actuation rod464 of the lower actuator telescoping through the rod 462 of the upperactuator 402 and the feature 440 of the upper substrate support 442, asshown in FIG. 4C.

Returning again to FIG. 2, a pressure control system 250 is coupled tothe load lock chamber 104 to control the pressure within the internalvolumes 220 of the body assembly 202. The pressure control system 250generally includes a gas source 252 and an exhaust system 254. The gassource 252 is coupled to at least one inlet port 260 formed through thechamber body assembly 202. The gas source 252 provides a vent gasutilized to raise and/or regulate pressure within the internal volume220 of the chamber body assembly 202. For example, the gas source 252may flow vent gas into the internal volumes 220 of the transfer cavities208, 210 to facilitate transfer of the substrate 116 from a vacuumenvironment to an ambient environment. In one embodiment, the vent gascomprises at least one of nitrogen, helium, air or other suitable gas.Optionally, the heating cavity 212 may not include an inlet port as, inone embodiment, the cavity 212 may be constantly maintained atoperational vacuum pressure.

An inlet control valve 256 is disposed between the gas source 252 andthe inlet port 260 to selectively control the flow of vent gases intothe internal volumes 220 of the body assembly 202. The inlet controlvalve 256 is capable of providing a substantially leak-tight seal undervacuum conditions. In one embodiment, the gas source 252 is configuredto control the attributes of the vent gas, such as the flow rate,temperature and/or humidity of the vent gas.

In the embodiment depicted in FIG. 2, the inlet port 260 is coupled toone or more diffusers 240 by a vent passage 238. The diffusers 240 areformed in an interior side of the top plate 204 (or other plate), suchthat gas flowing into the internal volume 220 is directed toward the topof the substrate 116. This arrangement beneficially assists in coolingthe substrate 116 while venting the load lock chamber 104 afterprocessing the substrate 116.

In one embodiment, the diffuser 240 is formed in a recess 232 defined inthe bottom surface of the plates 204, 298. A cap 244 covers the recess232 to define a plenum 242 in the plates. A connecting hole 236 fluidlycouples the plenum 242 to the vent passage 238. A plurality of apertures276 are formed through the cap 244 to allow vent gases to flow from thegas source 252 through plenum 242 and into the interior volume 220, asillustrated by arrows 234. Although the diffusers 240 are primarilyintended to direct venting gases into the load lock chamber 104, it iscontemplated that the diffusers 240 may also be utilized to evacuate theinternal volume 220 of the chamber 104.

The exhaust system 254 is generally coupled to at least one exhaust port262 formed through the chamber body assembly 202. The exhaust system 254is configured to remove gases from the internal volume 220 of the loadlock chamber 104. The exhaust system 254 may include one or more vacuumpumps (not shown) and may be ultimately coupled to the facilitiesexhaust system (also not shown). For example, the exhaust system 254 maypump out gas from the internal volume 220 to facilitate transfer of thesubstrate 116 from an ambient environment to a vacuum environment.

An exhaust control valve 258 is disposed between the exhaust system 254and the exhaust port 262 to selectively control the flow of gasesexiting the internal volume 220 of the body assembly 202. The exhaustcontrol valve 258 is typically similar to the inlet control valve 256and is capable of providing a substantially leak-tight seal under vacuumconditions.

A controller 280 is coupled to the load lock chamber 104 to control theoperation thereof. The controller 280 includes a central processing unit(CPU) 282, support circuits 286 and memory 284. The CPU 282 may be oneof any form of computer processor that can be used in an industrialsetting for controlling various chambers and subprocessors. The supportcircuits 286 are coupled to the CPU 282 for supporting the processor ina conventional manner. These circuits include cache power supplies,clock circuits, input/output circuitry, subsystems, and the like. Thememory 284 is coupled to the CPU 282. The memory 284, orcomputer-readable medium, may be one or more of readily available memorysuch as random access memory (RAM), read only memory (ROM), floppy disk,hard disk, or any other form of digital storage, local or remote.

A method, for example one of the substrate transfer methods describedbelow, is generally stored in the memory 284, typically as a softwareroutine. The software routine may also be stored and/or executed by asecond CPU (not shown) that is remotely located from the hardware beingcontrolled by the CPU 282.

Although the method of the present invention is discussed as beingimplemented as a software routine, some of the method steps that aredisclosed herein may be performed in hardware as well as by the softwarecontroller. As such, the invention may be implemented in software asexecuted upon a computer system, in hardware as an application specificintegrated circuit or other type of hardware implementation, or acombination of software and hardware.

FIG. 6 is a flow diagram of one embodiment of a method 600 fortransferring substrates between an atmospheric environment and a vacuumenvironment. The method 600 may be stored in memory 284, executed by thecontroller 280, and be practiced utilizing the load lock chamber 104described herein. It is also contemplated that the method 600 may bepracticed in other suitably adapted load lock chambers.

The method 600 begins at step 602 by transferring a first unprocessedsubstrate from an atmospheric environment (e.g., the factory interface102) to the first substrate support 218 disposed in the first transfercavity 208 formed in the load lock chamber body assembly 202. The firsttransfer cavity 208 additionally has a first processed substratepositioned therein on the second substrate support 218. At step 604, thefirst substrate transfer cavity is evacuated to a pressure substantiallyequal to an adjoining vacuum environment (e.g., the transfer chamber106). During the evacuation step 604, the first processed substrate maybe cooled. In one embodiment, the first processed substrate may becooled by moving the substrate to a position very close and/or touchingthe floor of the first substrate transfer cavity. As the floor of thefirst substrate cavity has a cooling fluid circulating in a passage 224formed therein, the first processed substrate is efficiently and rapidlycooled.

At step 606, the first unprocessed substrate is transferred into thevacuum environment from the first substrate support. At step 608, asecond processed substrate is transferred from the vacuum environment tothe first substrate support disposed above the first processedsubstrate.

The method may continue at step 610 by venting the first substratetransfer cavity and transferring the first processed substrate from thesecond substrate support to the atmospheric environment (e.g., thefactory interface 102). At step 612, steps 602 through 610 may berepeated to move additional substrates between the atmospheric andvacuum environments. Notably, the method 600 requires hot substratesreturning to the factory interface from the transfer chamber to bemaintained in the load lock chamber through at least two venting cycles.This facilitates fast delivery of unprocessed substrates into thetransfer chamber while allowing extended time in the load lock chamberfor processed substrates to ensure uniform cooling without unduegeneration of thermal stresses, condensation or other defect.

Moreover, in order to minimize creation of thermal gradients duringcooling and/or condensation on the processed substrate, the processedsubstrate may be maintained in a first position relative to the floor(or ceiling) of the substrate transfer cavity during the first transfercycle while the substrate is at an elevated temperature, then moved to asecond elevation closer to the floor (or ceiling) of the transfer cavityduring the second transfer cycle when the substrate is at a much coolertemperature. For example, the substrate may be cooled from about 250degrees Celsius to about 140 degrees Celsius during the first transfercycle while being relatively spaced from the cavity flood and/orceiling. Once at a lower temperature, the substrate may be cooled to atemperature below 140 degrees Celsius during the second transfer cycleby moving the substrate to a position relatively closer or in contactwith the cooled floor (or ceiling) of the load lock chamber body.

FIG. 7 is a flow diagram of another embodiment of a method 700 fortransferring substrates between an atmospheric environment and a vacuumenvironment. In one embodiment, the method 700 begins at step 702 bytransferring an unprocessed substrate from an atmospheric environment toa first substrate support disposed in the first transfer cavity 208 of aload lock chamber body assembly 202. At step 702, the first substratetransfer cavity is evacuated while having the first unprocessedsubstrate disposed therein. At step 706, the first unprocessed substrateis transferred from the first substrate support into the vacuumenvironment. At step 708, the unprocessed substrate is transferred to asecond substrate support disposed in a heating cavity 212 of the loadlock chamber body assembly 202. At step 708, the unprocessed substratemay optionally have one or more processes performed prior to transfer tothe heated cavity 212. At step 710, the first unprocessed substrate isheated in the heated cavity 212. The method continues at step 712 bytransferring the heated first unprocessed substrate from the secondsubstrate support disposed in the heated cavity 212 to the vacuumenvironment and processing the substrate.

At step 710, the substrate may be heated using radiant heaters, such aslamps and/or a resistively heated plate. The heating may occur while theheating cavity 212 is maintained in a vacuum condition. Alternatively,the heating cavity 212 may be isolated from the vacuum environment andfilled with a heat transfer medium such as nitrogen and/or helium tofurther enhance heat transfer to the first unprocessed substrate.

FIG. 8 is another embodiment of a load lock chamber 800. The load lockchamber 800 includes a body 802 having an upper transfer cavity 806 anda lower transfer cavity 808 defined therein. The construction of thechamber body 802 may be similar to the chamber body assembly 202described above.

The upper transfer cavity 806 generally has four substrate transferslots 810, 812, 820, 822 defined therein. Each substrate transfer slotis defined by a substrate support 818 which includes a plurality of pins226 for supporting one substrate 116 thereon. An isolation plate 830 isdisposed between the second substrate transfer slot 812 and the thirdsubstrate transfer slot 820 to bifurcate the upper transfer cavity 806into cooling and heating regions. The heating region generally includesthe first and second substrate transfer slots 810, 812, while thecooling region generally includes the third and fourth substratetransfer slots 820, 822 positioned therein.

The isolation plate 830 includes channels 832 coupled to a heat transferfluid source 834. The fluid source 834 circulates a heat transfer fluidthrough the isolation plate 830 to maintain the plate 830 at apredefined temperature. Moreover, the heat transfer fluid flowingthrough the channels 832 allows the heat transfer plate 830 tosubstantially minimize thermal crosstalk between the heating and coolingregions defined on either side of the isolation plate 830 within theupper transfer cavity 806.

Substrates supported in the heating region of the upper transfer cavity806 are heated by on or more heaters 866. The heater 866 is disposed onat least one of the ceiling or floor of the upper transfer cavity 806.The heater 866 may be a resistive heating element or lamp. The heaters866 are coupled to a source 868 such that the thermal energy provided bythe heaters 866 may be controlled as discussed above.

Substrates supported in the cooling region of the upper transfer cavity806 are cooled by the isolation plate 830 and/or a thermally regulatedinterior wall 828 which separates the upper and lower transfer cavities806, 808. The wall 828 generally includes one or more passages 824through which a heat transfer fluid provided by a source 826 iscirculated. It is contemplated that the cooling region may be definedabove the isolation plate 830 while the heating region is defined belowthe isolation plate 830. The heat transfer cavity 808 is similarlyconstructed.

A pressure regulating system 250 is provided to control the pressurewithin the transfer cavities 808, 806 as described above. Each cavity806, 808 includes one substrate access port 816 facing the factoryinterface 102 and a single second substrate access port 816 facing thetransfer chamber 106. Thus, each of the substrate storage slots 810,812, 820, 822 defined in the transfer cavities 806, 808 may berobotically accessed through a single port 816. Each substrate accessport is selectively sealed by a single valve door 814 that isselectively opened and closed by an actuator 804. The slit valve doors814 may be constructed as described above.

FIG. 9 is a flow diagram of another embodiment of a method 900 fortransferring substrates between an atmospheric environment and a vacuumenvironment. The method 900 is described with reference to the load lockchamber 800, but may also be practiced on other load lock chambers.

Column 902 of the method 900 illustrates the sequential time betweeneach step of the method 900. It is noted that the time is arbitrary andmerely representative of relative time required for each step. The timerequired for each step is dependent upon the size of the substrate, thevolume being evacuated and vented and the heat transfer efficiency ofthe chamber. Column 904 indicates the pressure status of the transfercavity of the load lock chamber. In the method 900, flow through theupper transfer cavity of the processing of the load lock chamber 800 isdescribed. A similar process may be performed in the lower transfercavity. It is also contemplated that embodiments of the method 900 mayalso be performed in other load lock chambers.

Column 906 describes the actions taken at each time step for substratesdisposed in slots 1 and 2 of the upper transfer cavity. Column 908describes the action taken for the substrates disposed in slots 3 and 4of the upper substrate transfer cavity.

FIG. 10 depicts a graph illustrating a vacuum condition of the uppertransfer cavity of the load lock chamber 800 of FIG. 8 during differentstages of the method 900 for transferring substrates between anatmospheric environment and a vacuum environment. Vertical axis 1006depicts pressure while horizontal axis 1008 depicts time. Trace 1002 isrepresentative of the pressure within the slots 1 and 2 while trace 1004is representative of the pressure within slots 3 and 4.

The method begins at time zero where the cavity is at atmosphericpressure. Two cool substrates are removed from slots 1 and 2 andreplaced with two new substrates from the factory interface 102 by theatmospheric robot 112. Two processed substrates (i.e., returning fromprocessing in one or more of the processing chambers 108) remain inslots 3 and 4 to undergo cooling. At time 0:30, the upper transfercavity is pumped down to vacuum. The two new substrates disposed inslots 1 and 2 are heated while the two substrates disposed in slots 3and 4 continue to be cooled. At time 1:30, the upper transfer cavity isat vacuum and the slit valve door is opened to the transfer chamber. Theheated substrates disposed in slots 1 and 2 are exchanged with processsubstrates by the vacuum robot 110. The two processed substratesdisposed in slots 3 and 4 continue to be cooled. Thus, at this time,slots 1-4 have processed substrates disposed therein.

At time 2:00, the upper transfer cavity is sealed from the transferchamber and vented to atmosphere. The two process substrates disposed inslots 1 and 2 are cooled while the two substrates in slots 3 and 4continue cooling. At time 6:00, the upper transfer cavity is atatmospheric pressure, and the slit valve door is opened such that theupper transfer cavity is accessible to the atmospheric robot 112. Thetwo substrates disposed in slots 1 and 2 continue to be cooled while thetwo cooled substrates disposed in slots 3 and 4 are removed by theatmospheric robot and replaced with two new substrates obtained from thecassettes 114.

At time 6:30, the upper transfer cavity is pumped down to vacuum. Thetwo substrates disposed in slots 1 and 2 continue to be cooled while thetwo new substrates disposed in slots 3 and 4 are heated. At time 7:30,the upper transfer cavity is at vacuum, and the slit valve doorseparating the load lock chamber separating the upper transfer cavityfrom the transfer chamber is opened. The two substrates disposed inslots 1 and 2 continue to be cooled while the heated substrates disposedin slots 3 and 4 are exchanged with process substrates by the vacuumrobot. Thus, at this time, slots 1-4 have processed substrates disposedtherein.

At time 8:00, the upper transfer cavity is vented to atmosphere. The twosubstrates disposed in slots 1 and 2 continue cooling while the twosubstrates disposed in slots 3 and 4 begin cooling. At time 12:00, theupper transfer cavity is at atmospheric pressure, and the slit valvedoor separating the upper transfer cavity from the factory interface isbe opened allowing the process to begin again.

Thus, a load lock chamber and method for transferring substrate betweenvacuum and ambient environment are provided. Double cycle cooling allowsthe substrate to be cooled at a rate that prevents thermal stress.Heating and cooling the substrates in separate chambers beneficiallypromote temperature uniformity by minimizing and isolating sources ofthermal contamination. Moreover, since the venting cycle iscomparatively long relative to the pump down cycle, the heating andcooling events and time are new decoupled since they are performed inseparate chambers, which add process flexibility and enables targetedoptimization of heating and cooling processes.

While the foregoing is directed to the preferred embodiment of thepresent invention, other and further embodiments of the invention may bedevised without departing from the basic scope thereof. The scope of theinvention is determined by the claims which follow.

1. A method for transferring substrates between an atmosphericenvironment and a vacuum environment, comprising: transferring a firstunprocessed substrate from an atmospheric environment onto a firstsubstrate support disposed in a first substrate transfer cavity formedin a load lock chamber body, the first transfer cavity having a firstprocessed substrate that was processed in the vacuum environmentpositioned on a second substrate support; evacuating the first transfercavity containing the first unprocessed substrate and the firstprocessed substrate; transferring the first unprocessed substrate into avacuum environment from the first substrate support; and transferring asecond processed substrate that was processed in the vacuum environmentfrom the vacuum environment onto the first substrate support.
 2. Themethod of claim 1 further comprising: venting the first substratetransfer cavity; and transferring the first processed substrate from thesecond substrate support to the atmospheric environment.
 3. The methodof claim 2 further comprising: transferring a second unprocessedsubstrate onto the second substrate support from the atmosphericenvironment evacuating the first substrate transfer cavity containingthe second unprocessed substrate and the second processed substrate;transferring the second unprocessed substrate from the second substratesupport into the vacuum environment; transferring a third processedsubstrate that was processed in the vacuum environment to the secondsubstrate support from the vacuum environment; venting the firstsubstrate transfer cavity containing the third processed substrate andthe second processed substrate; transferring the second processedsubstrate from the first substrate support to the atmosphericenvironment; transferring a third unprocessed substrate from theatmospheric environment onto the first substrate support; and evacuatingthe first substrate transfer cavity containing the third unprocessedsubstrate and the third processed substrate.
 4. The method of claim 1further comprising: transferring a second unprocessed substrate from theatmospheric environment onto a third substrate support disposed in asecond substrate transfer cavity formed in the load lock chamber body,the second transfer cavity having a third processed substrate that wasprocessed in the vacuum environment positioned on a fourth substratesupport; evacuating the second transfer cavity; transferring the secondunprocessed substrate into the vacuum environment from the thirdsubstrate support; and transferring a fourth processed substrate thatwas processed in the vacuum environment from the vacuum environment tothe third substrate support.
 5. The method of claim 4 furthercomprising: venting the second substrate transfer cavity; andtransferring the third processed substrate from the fourth substratesupport to the atmospheric environment.
 6. The method of claim 5 furthercomprising: transferring a third unprocessed substrate onto the fourthsubstrate support from the atmospheric environment; evacuating thesecond substrate transfer cavity containing the third unprocessedsubstrate and the fourth processed substrate; transferring the thirdunprocessed substrate from the fourth substrate support into the vacuumenvironment; transferring a fifth processed substrate that was processedin the vacuum environment onto the fourth substrate support from thevacuum environment; venting the second substrate transfer cavitycontaining the fourth and fifth processed substrates; transferring thefourth processed substrate from the third substrate support to theatmospheric environment; transferring a third unprocessed substrate fromthe atmospheric environment to the third substrate support; andevacuating the second substrate transfer cavity containing the thirdunprocessed substrate and the fifth processed substrate.
 7. The methodof claim 1 further comprising: cooling the first processed substrate. 8.The method of claim 7, wherein cooling further comprises: moving thefirst processed substrate proximate to at least one of a floor orceiling of the first transfer cavity.
 9. The method of claim 8, whereinmoving further comprises: placing the first processed substrate incontact with the load lock chamber body.
 10. The method of claim 1further comprising: transferring the first unprocessed substrate fromthe vacuum environment into a heating chamber formed in the chamberbody.
 11. The method of claim 10, wherein heating further comprises:heating the substrate under vacuum conditions.
 12. The method of claim10, wherein heating further comprises: sealing the heating chamber froma transfer chamber; and raising the pressure within the heating chamber.13. The method of claim 10 further comprising: transferring the heated,unprocessed substrate from the heating chamber into the vacuumenvironment.
 14. The method of claim 1, wherein the first substratesupport and the second substrate support are vertically aligned withinthe first substrate transfer cavity.
 15. The method of claim 14, furthercomprising selectively adjusting the vertical alignment of the first andsecond substrate supports, wherein the first and second substratesupports are independently movable.
 16. The method of claim 1, whereinthe first substrate support and the second substrate support arevertically movable relative to each other within the first substratetransfer cavity.
 17. A method for transferring substrates between anatmospheric environment and a vacuum environment, comprising:transferring a first unprocessed substrate from an atmosphericenvironment onto a first substrate support disposed in a first substratetransfer cavity formed in a load lock chamber body, the first substratetransfer cavity having a first processed substrate that was processed inthe vacuum environment positioned on a second substrate support;evacuating the first transfer cavity containing the first unprocessedsubstrate and the first processed substrate; transferring the firstunprocessed substrate to a vacuum environment from the first substratesupport; and transferring a second processed substrate that wasprocessed in the vacuum environment from the vacuum environment to thefirst substrate support, wherein the first processed substrate is movedproximate to the load lock chamber body using the first substratesupport when the first processed substrate has been relatively cooled,thereby facilitating heat exchange between the first processed substrateand the load lock chamber body.
 18. The method of claim 17, wherein thefirst processed substrate is moved in contact with the load lock chamberbody.